net: systemport: Pre-calculate and utilize cb->bd_addr

There is a 1:1 mapping between the software maintained control block in
priv->rx_cbs and the buffer address in priv->rx_bds, such that there is
no need to keep computing the buffer address when refiling a control
block.

Signed-off-by: Florian Fainelli <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

drivers/net/ethernet/broadcom/bcmsysport.c

···
 	}
 
 	dma_unmap_addr_set(cb, dma_addr, mapping);
-	dma_desc_set_addr(priv, priv->rx_bd_assign_ptr, mapping);
-
-	priv->rx_bd_assign_index++;
-	priv->rx_bd_assign_index &= (priv->num_rx_bds - 1);
-	priv->rx_bd_assign_ptr = priv->rx_bds +
-		(priv->rx_bd_assign_index * DESC_SIZE);
+	dma_desc_set_addr(priv, cb->bd_addr, mapping);
 
 	netif_dbg(priv, rx_status, ndev, "RX refill\n");
 
···
 	unsigned int i;
 
 	for (i = 0; i < priv->num_rx_bds; i++) {
-		cb = &priv->rx_cbs[priv->rx_bd_assign_index];
+		cb = &priv->rx_cbs[i];
 		if (cb->skb)
 			continue;
 
···
 
 static int bcm_sysport_init_rx_ring(struct bcm_sysport_priv *priv)
 {
+	struct bcm_sysport_cb *cb;
 	u32 reg;
 	int ret;
+	int i;
 
 	/* Initialize SW view of the RX ring */
 	priv->num_rx_bds = NUM_RX_DESC;
 	priv->rx_bds = priv->base + SYS_PORT_RDMA_OFFSET;
-	priv->rx_bd_assign_ptr = priv->rx_bds;
-	priv->rx_bd_assign_index = 0;
 	priv->rx_c_index = 0;
 	priv->rx_read_ptr = 0;
 	priv->rx_cbs = kcalloc(priv->num_rx_bds, sizeof(struct bcm_sysport_cb),
···
 	if (!priv->rx_cbs) {
 		netif_err(priv, hw, priv->netdev, "CB allocation failed\n");
 		return -ENOMEM;
+	}
+
+	for (i = 0; i < priv->num_rx_bds; i++) {
+		cb = priv->rx_cbs + i;
+		cb->bd_addr = priv->rx_bds + i * DESC_SIZE;
 	}
 
 	ret = bcm_sysport_alloc_rx_bufs(priv);

drivers/net/ethernet/broadcom/bcmsysport.h

···
 
 	/* Receive queue */
 	void __iomem		*rx_bds;
-	void __iomem		*rx_bd_assign_ptr;
-	unsigned int		rx_bd_assign_index;
 	struct bcm_sysport_cb	*rx_cbs;
 	unsigned int		num_rx_bds;
 	unsigned int		rx_read_ptr;